ABSTRACT-Experiments conducted in the early 1980s on a very small
selection of modern artists' pigments showed that several pigments
fade dramatically if exposed to ozone at the levels found in Los
Angeles photochemical smog. The objective of this research project
is to provide a comprehensive assessment of the full scope of this
fading hazard to works of art, and to determine the methods that
can be used to protect works of art from damage due to photochemical
oxidants. In order to achieve this objective, research is progressing
on several fronts. Accomplishments to date are summarized briefly,
followed by several appendices that provide more detailed information
on some aspects of the research.

ABSTRACT-Recently it has been shown that several artists' pigments
fade in the absence of light if exposed to atmospheric ozone at
the levels found in Los Angeles photochemical smog. In this study,
a large number of organic artists' pigments have been examined to
further assess the scope of this fading hazard to works of art.
It was found that all of the alizarin-derived pigments are susceptible
to fad ing in the presence of ozone. Several organic red pigments
were identified that are much more ozone-resistant than the alizarin
lakes, including quinacridone reds and BON arylamide reds. The question
of ozone exposure in museums is reviewed. It is shown that indoor
ozone concentrations may be as high as 50% to 70% of those outdoors,
and that long-term average outdoor ozone levels in many parts of
the world are nearly as high as those found in geographic locations
with well-known pho tochemical air pollution problems.

ABSTRACT-During the summers of 1984 and 1985, two matched ultraviolet
pho tometric ozone monitors were used to take simultaneous indoor/outdoor
ozone measurements at eleven institutions housing cultural properties
over a period totaling thirty-eight days. These sites were picked
to represent a wide range of building types in the Los Angeles area
and 100 miles to the south in San Diego, California. Each building
and its ventilation system was documented. A hot wire anemometer
was used to measure air flow into and out of ventilation ducts,
doors, and windows at each site. In stagnant areas, air exchange
rates were evaluated from standard engineering estimates for air
infiltration. From the accumulated information, the air exchange
rates and retention times for ozone destruction by reaction with
building surfaces could be determined.

ABSTRACT-The colorants alizarin and Alizarin Crimson (a calcium-alu
minum lake pigment) and their simple structural homologues anthra-quinone
were deposited on silica gel, cellulose, and Teflon substrates and
exposed in the dark to ozone in purified air (0.4 ppm O3 for 95
days). Exposed and control samples were analyzed by mass spectrometry
. Alizarin Crimson reacted with ozone on all substrates, yielding
phthalic acid (major), benzoic acid (minor), and other minor and
unidentified products. Anthraquinone did not react with ozone irrespective
of conditions. Alizarin did not react on Teflon or cellulose but
reacted on silica gel to yield phthalic acid (major) and other products.
A chemical mechanism responsible for the fading of these alizarin-based
colorants by ozone is suggested that is consistent with the products
distribution, the observed reactivity sequence, and the observed
substrate-specific effects. The possible application of this work
to predicting the ozone fastness of other alizarin-related pigments
is discussed briefly.

ABSTRACT-The organic colorant curcumin [1,7-bis(4-hydroxy-3 methoxy-phenyl)-1,6-heptadiene-3,4-dione]
was exposed to ozone in purified air in the dark, and the exposed
samples were analyzed by mass spectrometry. The major reaction products
included vanillin (4-hydroxy-3-methoxybenzaldehyde ) and vanillic
acid (4-hydroxy-3-methoxybenzoic acid) . These products and the
corresponding loss of chromophore (i.e. fading of curcumin) are
consistent with a reaction mechanism involving electrophilic addition
electrophilic addition of ozone onto the olefinic bonds of curcumin. Vanillin and vanillic acid did not react with ozone under the
con ditions of this study.

ABSTRACT-Indigo , dibromoindigo , and colorants containing thioindigo
and tetrachlorothioindigo were exposed in the dark to dry, purified
air containing ozone (10 ppm) for four days, and the exposed samples
were analyzed by mass spectrometry. Under the conditions employed,
indigo and dibromoindigo were entirely consumed, and the major reaction
products were isatin and isatoic anhydride from indigo and bromoisatin
and bromoisatoic anhydride from dibromoindigo. Thioindigo and its
chloroderivative also reacted with ozone, though at a slower rate;
the corresponding substituted isatins and anhydrides were tentatively
identified as reaction products.

ABSTRACT-Triphenylmethane compounds were exposed in the dark to
ozone in air (10 ppm for 4 days), and the exposed samples were analyzed
by mass spectrometry. There was no evidence for reaction between
ozone and triphenyl-methane and between ozone and the triphenylcarbinol
pararosaniline base . In contrast, the triphenylmethane cationic
dye Basic Violet 14 yielded substituted benzophenones and other
aromatic compounds. These products are consistent with a mechanism
involving ozone addition on the unsaturated carbon-carbon bond.
The results are briefly discussed in terms of the ozone-fastness
of triphenylmethane dyes used as artists' pigments and industrial
colorants.

ABSTRACT-A general mathematical model is presented for predicting
the concentrations of chemically reactive compounds in indoor air.
The model accounts for the effects of ventilation, filtration, heterogeneous
removal, direct emission, and photolytic and thermal chemical reactions.
The model is applied to the induction of photochemically reactive
pollutants into a museum gallery, and the predicted NO, NOx-NO,
and O3 concentrations are compared to measured data. The model predicts
substantial production of several species due to chemical reaction,
including HNO2, HNO3, NO3, and N2O5. Circumstances in which heterogeneous
chemistry may assume particular importance are identified and include
buildings with glass walls, indoor combustion sources, and direct
emission of olefins.

ABSTRACT-This report details the results of an ozone exposure experiment
per formed on a large number of traditional natural organic colorants
applied to watercolor paper with no binder. These colorants were
exposed in an environmental chamber to an atmosphere containing
0.397-0.007 parts per million (ppm) ozone at 72 °F and 50%
RH in the absence of light for 12 weeks. This ozone concentration
is typical of that found in the Los Angeles atmosphere during a
heavy smog episode. The total ozone dose delivered to the samples
is equivalent to about four years of exposure to outdoor air in
Los Angeles or to about eight years inside a typical air-conditioned
building in Los Angeles. The ozone sensitivity of these colorant
systems was evaluated by monitoring the color changes which occurred
during the exposure. Almost all colorant systems tested showed some
degree of fading after ozone exposure, and a few of these (curcumin,
dragon's blood, indigo, and madder lake) should be considered very
ozone-fugitive.

ABSTRACT-The colorfastness of several traditional Japanese colorants
upon exposure to atmospheric ozone was tested in a chamber exposure
experiment. Samples, in the form of colorants applied to paper,
dyes on silk cloth, and colorants on a 19th century Japanese woodblock
print, were exposed to an atmosphere containing 0.40 part per million
ozone at 22 ºC and 50% RH, in the absence of light, for 12
weeks. Color differences, calculated from the measured diffuse reflectance
spectra, were used to assess the rate and extent of the ozone fading.
Of the colorants applied to paper, orpiment was the only inorganic
pigment that showed severe color loss after ozone exposure. Several
organic colorants on paper also reacted, including the widely used
plant colorants ai (indigo) and ukon (turmeric). The wood block
print, produced using the plant-derived colorants beni (safflower),
ai (indigo), shio (gamboge), and aigami (dayflower) showed significant
ozone fading only in the blue and green areas, which contain ai.
Several of the dyed silk cloths also exhibited some color change
in this experiment, suggesting that prolonged exposure to atmos
pheric ozone could pose a risk to these materials as well.

ABSTRACT-Nitrogen dioxide is a common air pollutant formed in the
atmosphere from the nitric oxide emissionsfrom fuel combustion sources.
Samples of organic and inorganic pigments, iron inks on paper, and
traditional Japanese tex tile dyes mordanted onto silk were exposed
to 0.50 ppm NO2 in air for 12 weeks. Ten of the traditional natural
organic colorant samples on paper tested showed mea surable color
changes (DE>2) as a result of the NO2 exposure, as did several
of the an thraquinone-based synthetic organic pigments. The arsenic
sulfide pigments orpiment and realgar and the iron inks tested showed
considerable color changes (DE >5) over the 12-week period. Nine
of the 23 Japanese dyed silk cloths changed color by at least two
DE units. An NO2 dose (concentration times duration of exposure)
of the magnitude employed in this experiment would be experienced
in side an unprotected museum in downtown Los Angeles over about
a two-year period, and in many other cities within a period of five
to six years.

ABSTRACT-A chamber exposure experiment has been conducted to examine
the effect of binders and coatings that might be used to protect
artists' pigments from oxidation by atmospheric ozone. Alizarin
Crimson pigment was used as a sensitive colorimetric detector of
the penetration of ozone or its reaction products through the binder
and coating systems tested. Binder systems studied in cluded acrylics,
beeswax, casein, egg tempera, oils, and varnishes. Coatings tested
included acrylic emulsions, methacrylates, beeswax, varnishes, shellac,
and ethulose (a consolidant). Alizarin Crimson dry pigment airbrushed
onto a white painted background with no binder or coating typically
faded severely (DE <15) under the conditions of this experiment
(0.40 ppm O3 for 12 weeks at 22 °C and 52% RH). In contrast,
many of the binder and coating systems tested were capable of limiting
the fading of an equivalent Alizarin Crimson sample to a color change
of DE < 1 during identically the same exposure conditions. Several
binders and coatings did prove to be less effective than others.
In particular, many of the acrylic emulsion coatings failed to offer
adequate protection to the Alizarin Crimson pigment samples tested.

ABSTRACT-Organic colorants that have been shown to be ozone-fugitive,
such as curcumin, indigo, alizarin lake, and triphenylmethane dyes,
were exposed to 0.3-0.4 ppm of ozone for 12 weeks in purified air.
Exposed and control samples were analyzed by mass spectroscopy using
a Kratos Scientific Instruments MS25 hexapole mass spectrometer
operated either in chemical ionization (CI) or electron impact (EI)
modes. The data from the investigation are reported here.

Cass, G. R., "Protection of Works of Art from Damage Due to Air
Pollution," American Chemical Society, Division of Environmental
Chemistry, Miami, Florida, September 10-15, 1989.

ABSTRACT-Damage to works of art can occur due to the intrusion
of outdoor air pollutants into the museum environment. In this presentation,
mathematical modeling approaches are described that can be used
to evaluate the effect of ventilation system redesign on indoor
pollutant levels. Other methods for protection of collections from
damage due to air pollution include the use of display cases, framing
under glass, pigment substitution, and application of coatings over
the works of art. A quantitative comparison will be presented, with
examples drawn from experience gained in studies of indoor ozone
and airborne particulate matter abatement.

ABSTRACT-Long-term preservation of the paper-based collections
at the National Archives requires that damage caused by environmental
conditions and atmospheric pollutants be prevented. Because these
documents, or at least their in formation content, must be retained
indefinitely, even very slow rates of deterioration caused by air
pollution could lead to unacceptable levels of accumulated damage
over a period of several hundred years. The problem of protecting
the National Archives inventory is thus quite different from the
question of protecting common consumer products from premature deterioration
over their short service lifetime. Standards adopted for acceptable
air quality outdoors therefore are not applicable, and separate
air quality objectives must be set that are suited to the problem
of long-term preservation of archival materials.

Preusser, F., and J. R. Druzik, "The Environmental Research at
the Getty Conservation Institute," Paper presented at the National
Archives and Record Administration, April 12, 1988.

ABSTRACT-Having recognized that control of the collection's environment
is the best preservation strategy, the Scientific Program of the
Getty Conservation Institute began in early 1984 to concentrate
the main part of its resources on research in the museum environment.
This research is done in the laboratories of the GCI and through
research contracts awarded to other institutions. The following
main areas of research are presently being pursued: comparative
measurements of indoor and outdoor con centrations of industrial
and domestic air pollutants (ozone, PAN, NOx, HNO3, HCl) and airborne
particulates (soil dust, road dust, sea salt H2SO4, aerosol, sulfate,
nitrate, and organic and elemental carbon). A mathematical model
has been developed for the calculation of the infiltration of these
pollutants into a building in relation to its architecture and ventilation
strategy.

a.) Survey of indoor generated air pollutants (at present carbonyls
and organic acids) in museums in the United States.

b.) Strategies for the control of pollutants in buildings, rooms,
and storage and display cases.

c.) Assessment of the damage to museum objects and archival materials
caused by outdoor- and indoor-generated pollutants.

d.) Passive and active methods for the control of relative humidity
in storage and display cases.

e.) The evaluation of the current generation of temperature and
humidity monitoring equipment.

ABSTRACT-In 1984, the Getty Conservation Institute (GCI) embarked
on a program of museum environmental research museum covering outdoor-generated
air pollution, indoor-generated pollution, and microenvironmental
studies. These three branches are further divided into surveys of
pollutant concentrations in buildings containing cultural and natural
history collections, materials damage assessments, and control strategies.
In the microenvironment, the targeted issues are humidity control
and monitoring, low-cost sealed display cases, biological control,
and selected topics in lighting. In separate but related areas the
GCI con ducts research in vibrational and shock effects, fumigation
research, and on bringing the conservator and mechanical engineer
closer together in the process of designing and retrofitting building
air conditioning systems. In this paper, for each area of research,
a brief background is presented in addition to where the GCI has
built upon it.

ABSTRACT-Air pollution has been known to cause damage to museum
objects for at least one hundred years. However, until recently,
little was known about the indoor concentrations of photochemical
oxidants in the museum environment or the potential risks they might
pose to museum collections. For this reason we began in the early
1980s to measure the indoor/outdoor (I/O) concentration ratios of
ozone in a selec tion of buildings which represented a range of
ventilation, architectural, and collection types. A computer model
was developed which predicted indoor ozone concentrations based
on a combination of building parameters, pollutant sources, and
loss mechanisms. In parallel, experiments were established that
exposed natural and synthetic colorants, on various substrates,
to ozone at concentrations found in Los Angeles photochemical air
pollution.

ABSTRACT-Ozone at the concentrations found in the indoor atmosphere
of many museums poses a fading hazard to the pigments used in works
of art. The ozone control problem faced by museum personnel is
unusual because indoor ozone exposure must be reduced to very low
levels in order to protect the collections from accumulated damage
over periods of 100 years or more. In the present study, methods
that can be used to protect museum collections from ozone damage
are evaluated. Control measures examined include pollutant removal
via ventilation system redesign, con struction of display cases
to protect the works, framing of paintings, prints, and water colors
behind glass, selection of ozone-resistant pigments, and application
of binder and coatings that protect ozone-sensitive pigments.